If the lead group goes to surge-stop-surge, then Kristoff and the 2 Astanas (who got within 20s or so before PhilGil got on the front, iirc) and possibly even the group behind them with Degenkolb could have got back on. If one of them could have got away alone, a la Terpstra in Roubaix 14, then yes, that’s ideal, but almost any other 1 v 1 or 1 v 2 matchup in the group (Stybar, Gilbert or Lampaert v any of Sagan, GVA, Matthews, Demarre, Debuschere, Stuyven, etc) is no more likely a win for QuickStep than Viviani vs all of them, probably less so.
Also, Viviani’s probably not going to Roubaix, or RVV, or the Ardennes. Maaaaaybe Amstel. This was probably the team’s last chance to give him a big classic win this season (at least until Paris-Tours). Even if one of the other 3 could have worked out something, I have to give credit to QS for backing Viviani, and sticking to the plan. Maybe there is still some room for sentiment in cycling?